Structure adapted to traverse a fluid environment and method of retrofitting structure adapted to traverse a fluid environment

ABSTRACT

A structure adapted to traverse a fluid environment exerting an ambient fluid pressure is provided. The structure includes an elongate body extending from a root to a wingtip and encapsulating at least one interior volume containing an interior fluid exerting an interior fluid pressure that is different from the ambient fluid pressure. A method of retrofitting a structure adapted to traverse a fluid environment exerting an ambient fluid pressure, the structure comprising an elongate body extending from a root to a wingtip and having at least one interior volume is also provided. The method includes sealing the elongate body to encapsulate the at least one interior volume containing an interior fluid; associating at least one valve with the at least one interior volume; and modifying interior fluid content via the at least one valve to produce an interior fluid pressure that is different from the ambient fluid pressure.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/553,103 filed Aug. 23, 2017 which is a 371 of InternationalApplication No. PCT/CA2016/050195 filed Feb. 25, 2016, and InternationalApplication No. PCT/CA2016/050195 claims benefit of U.S. ProvisionalPatent Application Ser. No. 62/120,409 filed on Feb. 25, 2015, thecontents of which are incorporated in their entirety herein byreference.

FIELD OF THE INVENTION

The following relates generally to structures adapted to traverse fluidenvironments, and more particularly to a structure adapted to traverse afluid environment having an encapsulated fluid and a method forretrofitting

BACKGROUND OF THE INVENTION

Horizontal-axis wind turbines for generating electricity from rotationalmotion are generally comprised of one or more rotor blades each havingan aerodynamic body extending outwards from a horizontal shaft that issupported by, and rotates within, a wind turbine nacelle. The nacelle issupported on a tower which extends from the ground or other surface.Wind incident on the rotor blades applies pressure causing the rotorblades to move by rotating the shaft from which they extend about thehorizontal rotational axis of the shaft. The shaft is, in turn,associated with an electricity generator which, as is well-known,converts the rotational motion of the shaft into electrical current fortransmission, storage and/or immediate use. Horizontal-axis windturbines are generally very well-known and understood, thoughimprovements in their operation to improve the efficiency of powerconversion and their overall operational characteristics are desirable.

Incident wind at even low speeds can cause the rotor blades to rotatequickly. As would be well-understood, for a given rotational velocity,the linear velocity of a rotor blade is lowest in the region of itsroot—the portion of the rotor blade proximate to the shaft. Similarly,the linear velocity of the rotor blade is highest in the region of itswingtip—the portion of the rotor blade distal from the shaft.

Wind turbines are increasing in popularity in recent years as a means ofgenerating renewable energy. With this growth, there is increasinginterest in turbine components that are efficient to maintain in goodworking condition and in methods of efficiently manufacturing componentsfor the wind turbines and optimal locations for their operation havebeen subsequently declining, with these locations being limited.

It is known that current wind turbine blades are exposed to cyclicalgravitational loading and edgewise loading during rotation, also knownin the industry as ‘breathing’, where the blade expands and contracts.The expansions and contractions place stress on the bonding seams ofrotor blades at the leading and trailing edge, as well as along spar capand shear webs of the rotor blades. Through this continued stress,trailing edge, leading edge and transverse longitudinal cracks form,leading to eventually delamination and failures. The failures arethought to be a result of the Brazier effect, where over time thebreathing causes steadily increasing curvature in the bonding seam areasleading eventually to a threshold curvature after which the object beingcurved becomes unstable and forms somewhat of a kink.

Various proposals for addressing the stresses placed on rotor bladeshave been made.

For example, PCT International Patent Application No. PCT/DK2009/000149to Jensen, entitled “A REINFORCED WIND TURBINE BLADE” discloses anelongated reinforcing member connected to the shell of a wind turbineblade to improve the resistivity to compression forces experienced bythe blade.

United States Patent Application Publication No. 2007/0189903 to Eyb,entitled “WIND TURBINE ROTOR BLADE” discloses a carbon fibre reinforcedspar cap.

United States Patent Application Publication No. 2009/0129925 to Vronskyet al. entitled “WIND TURBINE BLADE LOAD SENSOR” discloses a windturbine rotor blade root load sensor configured to be internally mountedwithin an insert of a root portion of a wind turbine rotor. The sensoris positioned along the internal wall of the root of a rotor blade, anddetects torque and other bending forces.

United States Patent Application Publication No. 2009/0277266 to Wangentitled “METHODS AND APPARATUS FOR SENSING PARAMETERS OF ROTATINGBLADES” discloses a method for monitoring operating parameters of arotating blade having at least one sensor thereon, the sensoroperatively coupled to a data acquisition device, where the data relatesto blade acceleration measurements.

United States Patent Application Publication No. 2009/0232635 to Menkeentitled “INDEPENDENT SENSING SYSTEM FOR WIND TURBINES” discloses awireless sensing device for use in a wind turbine measuring multipleparameters and having an independent power source.

SUMMARY OF THE INVENTION

According to an aspect, there is provided a structure adapted totraverse a fluid environment exerting an ambient fluid pressure, thestructure comprising an elongate body extending from a root to a wingtipand encapsulating at least one interior volume containing an interiorfluid exerting an interior fluid pressure that is different from theambient fluid pressure.

In an embodiment, the elongate body is a rotor blade for a wind turbine.

According to another aspect, there is provided a method of retrofittinga structure adapted to traverse a fluid environment exerting an ambientfluid pressure, the structure comprising an elongate body extending froma root to a wingtip and having at least one interior volume, the methodcomprising sealing the elongate body to encapsulate the at least oneinterior volume containing an interior fluid; associating at least onevalve with the at least one interior volume; and modifying interiorfluid content via the at least one valve to produce an interior fluidpressure that is different from the ambient fluid pressure.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, to one of ordinary skill in the art, is set forthmore particularly in the remainder of the specification, includingreference to the accompanying figures wherein:

FIG. 1 is a side elevation view of a horizontal axis wing turbine,according to the prior art;

FIG. 2 is a front perspective view of a rotor blades for the turbine ofFIG. 1, in isolation, according to the prior art;

FIG. 3 is a cross-sectional view of a root end of the elongate body of arotor blade, according to an embodiment of the invention; and

FIG. 4 is an end view of the root end of the rotor blade of FIG. 3.

DETAILED DESCRIPTION

Reference will now be made in detail to the various embodiments of theinvention, one or more examples of which are illustrated in the figures.Each example is provided by way of explanation of the invention, and isnot meant as a limitation of the invention. For example, featuresillustrated or described as part of one embodiment can be used on or inconjunction with other embodiments to yield yet a further embodiment. Itis intended that the present invention includes such modifications andvariations.

The present patent application includes description of opportunities forimproving on the traditional aspects of a blade configuration for a windturbine.

FIG. 1 is a side elevation view of a horizontal axis wind turbine 10,according to the prior art. Wind turbine 10 includes a tower 100supported by and extending from a surface S, such as a ground surface.Supported by tower 100, in turn, is a nacelle 200 extendinghorizontally. A hub with a spinner 300 is rotatably mounted at a frontend of nacelle 200 and is rotatable with respect to nacelle 200 about arotation axis R. Spinner 300 receives and supports multiple rotor blades400 that each extend outwardly from spinner 300. Rotor blades 400 catchincident wind W1 flowing towards the wind turbine 10 and are caused torotate. Due to their being supported by spinner 300, rotor blades 400when rotating cause spinner 300 to rotate about rotation axis R therebyto cause rotational motion that can be converted in a well-known mannerinto usable electrical or mechanical power. In this sense, rotor blades400 are each structures adapted to traverse a fluid environment, wherethe fluid in this embodiment is ambient air. Nacelle 200 may berotatably mounted to tower 100 such that nacelle 200 can rotate about asubstantially vertical axis (not shown) with respect to tower 100,thereby to enable rotor blades 400 to adaptively face the direction fromwhich incident wind W_(i) is approaching wind turbine 10. A nose cone500 of generally a uniform paraboloidal shape is shown mounted to afront end of spinner 300 to deflect incident wind W_(i) away fromspinner 300.

FIG. 2 is a front perspective view of one of rotor blades 400 inisolation. Rotor blade 400 includes an elongate body that extends from aroot 410 through a main section 412 to terminate at a wingtip 414. Root410 extends from nacelle 200 when attached thereto or integratedtherewith, whereas wingtip 414 is the portion of the elongate body thatis distal to nacelle 200. The elongate body has a leading edge 420 and atrailing edge 430, where leading edge 420 leads trailing edge 430 whenrotor blade 400 is in motion rotating with nacelle 200 about rotationaxis R in the direction D. A suction side 440 of the elongate body isshown in FIG. 2, and a pressure side 450, shown in dotted lines, isopposite the elongate body from suction side 440.

FIG. 3 is a cross-sectional view of a root end 410A of the elongate bodyof a rotor blade 400A, according to an embodiment of the invention. Root410A is sealed with a seal S around its circumference thus completingthe encapsulation of an interior volume 470 within the elongate body.Interior volume 470 contains an interior fluid 472. According to theinvention, the interior fluid 472 is present in quantities within theinterior volume 470 so as to exert an interior fluid pressure IFP thatis different from the ambient fluid pressure AFP that is to be exertedby a fluid environment on the rotor blade 400A during its use.Preferably seal S can be selectively removed and put back into place forthe purpose of enabling access to the interior volume 470 formaintenance and the like.

In this embodiment, the interior fluid pressure IFP is less than theambient fluid pressure AFP, and the interior fluid 472 is primarilynitrogen. Nitrogen is lighter than air and its use as the interior fluid472 provides an overall weight of rotor blade 400A that is lighter thanif interior fluid 472 were to be air. However, in alternativeembodiments, interior fluid 472 could comprise air and/or other gasessuch as one or more noble gases including helium, neon, argon, krypton,xenon and/or other gases that preferably have low chemical reactivity.

Furthermore, in alternative embodiments, the interior fluid 472 couldexert an interior fluid pressure IFP that is more than the ambient fluidpressure AFP.

In the embodiment shown in FIGS. 3 and 4, a hydraulic injector pump 480is in fluid communication with a valve 482 associated with the elongatebody. In this embodiment, the valve 482 extends through seal S and isselectively configurable so as to enable interior fluid to be injectedinto or drawn from interior volume 470, as well as to selectivelyprevent neither entry nor egress of interior fluid, as desired. Inembodiments involving an interior fluid pressure IFP being less than theambient fluid pressure AFP, an alternative valve may be a check valvestructure that is configured with respect to the interior volume 470 toenable only drawing-out of interior fluid so as to selectively reducethe interior fluid pressure IFP. In embodiments involving an interiorfluid pressure IFP being more than the ambient fluid pressure AFP, analternative valve may be a check valve structure that is configured withrespect to the interior volume 470 to enable only injecting-in ofinterior fluid so as to selectively increase the interior fluid pressureIFP. While only one valve 482 is shown, more than one valve 482 may beemployed. For example, a structure according to alternative embodimentsmay have more than one interior volume encapsulating an interior fluid,and a valve may be provided for each interior volume.

The embodiment shown in FIGS. 3 and 4 further comprises a fluid pressuresensor 484 extending through seal S into the interior volume 470. Fluidpressure sensor 484 is in communication with a processing structure 486and provides processing structure 486 with electronic or electrical dataindicative of the level of the interior fluid pressure IFP of interiorfluid 472 within interior volume 470. Processing structure 486 is, inturn, in communication with hydraulic injector pump 480. Processingstructure 486 is configured with computer-readable software code storedon a computer readable medium to provide an alert system and to providelogic to enable processing structure 486 to serve as the controller of apressure regulation system such that, in the event that processingstructure 486 receives data indicative of the level of the interiorfluid pressure IFP rising above or dropping below a threshold level,processing structure 486 can generate an alert and/or can instructhydraulic injector pump 480 to inject more interior fluid 472 intointerior volume 470 via valve 482, or can trigger valve 482 to releaseinterior fluid thereby to bring the interior fluid pressure IFP to adesired level.

The alert generating system provides early warning to a wind turbineoperator as to damage to a rotor blade, since a rapid pressure change isan indication that a crack or hole has developed in the rotor blade.Operations can be rapidly ceased so that maintenance or replacement canbe done on demand, rather than necessarily in response to periodicmanual inspections that are costly in terms of time offline andpersonnel involvement.

In this embodiment, the valve 482 and the fluid pressure sensor 484 arepositioned at the root end of the elongate body to be located near tothe nacelle of a wind turbine that includes the structures as rotorblades extending from its hub. In this embodiment, both the processingstructure 486 and the hydraulic injector pump 480 are located within thehub. In the event that the communication between the hydraulic injectorpump 480 and the processing structure 486 is wireless and/or thecommunication between the fluid pressure sensor 484 is wireless, theprocessing structure 486 can be placed elsewhere, such as within thenacelle. The embodiment shown in FIGS. 3 and 4 is the result of aretrofitting of a known rotor blade. A rotor blade or other structureadapted to traverse a fluid environment exerting an ambient fluidpressure and having an elongate body extending from a root to a wingtipand having at least one interior volume may be retrofitted by sealingthe elongate body to encapsulate the at least one interior volumecontaining an interior fluid, associating a valve with the at least oneinterior volume; and modifying the interior fluid content via the valveto produce an interior fluid pressure that is different from the ambientfluid pressure.

In this embodiment, the sealing included sealing the elongate body atthe root, and the modifying interior fluid content included pumping airout of the at least one interior volume via the valve and pumpingnitrogen as into the at least one interior volume via the valve.

In alternative embodiments, retrofitting may include associating morethan one valve with the elongate body so as to modify interior fluidcontent of a number of encapsulated interior volumes of the structure.In embodiments, fluid may be simply pumped into an interior volume via avalve to increase the interior fluid pressure, or fluid may be simplypumped out of the interior volume via a valve to decrease the interiorfluid pressure.

In alternative embodiments, a new-build structure similar to thosedescribed herein may be formed so as to be sealed and with appropriatevalve structure for modifying the interior fluid content.

In embodiments, the interior fluid pressure IFP of the structure may bemaintained to be higher than the ambient fluid pressure AFP, such ashaving an interior fluid pressure of about 1 to about 100 pounds persquare inch (PSI). In such embodiments, the structure may be heavierthan those structures in which the interior fluid pressure IFP ismaintained to be lower than the ambient fluid pressure AFP. However,where the structure is a rotor blade for a wind turbine, momentum of aslightly heavier rotor blade in the face of gusty/erratic windconditions may be improved.

The beneficial aspects include longer structure life spans, particularlywhere the structure is a rotor blade for a wind turbine, and loweroperating costs for wind farm owners, increased warranty periods fornewly built rotor blades and a decreased overall cost to the windindustry.

Although embodiments have been described with reference to the drawings,those of skill in the art will appreciate that variations andmodifications may be made without departing from the spirit and scopethereof as defined by the appended claims.

The above-described rotor blade configurations for a horizontal-axiswind turbine can also be applied to one or more rotor blades usable forvertical-axis wind turbines, and both of any scale, or to one or morerotor blades usable in hydroelectric dam turbines, gas turbines, tidalturbines or airborne wind energy turbines or in other kinds of turbinesdealing with fluid flow whether of gas or of liquid.

The above-described rotor blade configurations may alternatively beemployed in aircraft such as commercial airliners, military jetaircraft, helicopter blades, helicopter wings, civilian airplanes,drones, and other similar aircraft. The invention or inventionsdescribed herein may be applied to wind turbines having fewer or moreblades than described by way of example in order to increase theoperational efficiency of a wind turbine, to decrease maintenance costs,and to increase the scalability and marketability of such wind turbines.

It is observed that commercial airliners, civilian airplanes, drones,helicopter wings would have a winglet of similar size ratio to those ofmodem commercial airliners, with an architecture that bends back beyondthe line of the trailing edge.

A structure as described herein may, as appropriate, contain additionalfeatures such as those described in PCT International Patent ApplicationNo. PCT/CA2015/050741 to Ryan Church entitled “STRUCTURE WITH RIGIDPROJECTIONS ADAPTED TO TRAVERSE A FLUID ENVIRONMENT”, and/or thosedescribed in PCT International Patent Application No. PCT/CA2015/050740to Ryan Church entitled “STRUCTURE WITH RIGID WINGLET ADAPTED TOTRAVERSE A FLUID ENVIRONMENT”, the contents of each of which areincorporated herein by reference.

Structures such as those described herein may apply equally well,mutatis mutandis, with such mutations as being relevant, including butnot limited to, commercial airliners, military jet aircraft, helicopterblades, helicopter wings, civilian airplanes, spacecraft, drones, andother things.

Furthermore, the structures disclosed herein are usable in other fluidenvironments besides ambient air, such as water environments, oilenvironments and so forth.

The structure adapted to traverse a fluid environment may be applied toa vertical-axis wind turbine.

The structure adapted to traverse a fluid environment may be applied toa hydroelectric dam turbine.

The structure adapted to traverse a fluid environment may be applied togas turbines.

The structure adapted to traverse a fluid environment may be applied totidal turbines.

The structure adapted to traverse a fluid environment may be applied toan airborne wind energy turbine.

The structure adapted to traverse a fluid environment may be applied toa commercial airliner.

The structure adapted to traverse a fluid environment may be applied toa military jet aircraft and to a spacecraft.

The structure adapted to traverse a fluid environment may be applied toa helicopter blade.

The structure adapted to traverse a fluid environment may be applied tohelicopter wings.

The structure adapted to traverse a fluid environment may be applied towings of civilian airplanes.

The structure adapted to traverse a fluid environment may be applied towings of a drone.

It should be noted that the term ‘comprising’ does not exclude otherelements or steps and the use of articles “a” or “an” does not exclude aplurality. Also, elements described in association with differentembodiments may be combined. It should be noted that reference signs inthe claims should not be construed as limiting the scope of the claims.

What is claimed is:
 1. A method of building a structure adapted totraverse a fluid environment exerting an ambient fluid pressure, thestructure comprising an elongate body extending from a root to a wingtipand having at least one interior volume, the method comprising:associating a pressure sensor for sensing a level of interior fluidpressure within the at least one interior volume with an alert system;sealing the elongate body to encapsulate the at least one interiorvolume containing an interior fluid; and configuring the alert system togenerate an alert in response to the pressure sensor detecting the levelof interior fluid pressure below, or above, a threshold level indicativeof structural damage to the elongate body.
 2. The method of claim 1,wherein the sealing the elongate body comprises sealing the elongatebody at the root with a releasable and reusable seal.
 3. The method ofclaim 1, further comprising: associating at least one valve with the atleast one interior volume; and modifying interior fluid content via theat least one valve to produce the level of interior fluid pressurebelow, or above, the threshold level indicative of structural damage tothe elongate body.
 4. The method of claim 3, wherein the modifyinginterior fluid content via the at least one valve comprises: pumpingfluid into the at least one interior volume via the at least one valve.5. The method of claim 3, wherein the modifying interior fluid contentvia the at least one valve comprises: pumping fluid out of the at leastone interior volume via the at least one valve; and pumping a noble gasinto the at least one interior volume via the at least one valve.
 6. Themethod of claim 4, wherein the fluid is nitrogen.
 7. The method of claim1, wherein the alert system is associated with a hub or a nacelleconnected to the elongate body.
 8. The method of claim 1, wherein thealert system wirelessly communicates with the pressure sensor.
 9. Amethod of building a structure adapted to traverse a fluid environmentexerting an ambient fluid pressure, the structure comprising an elongatebody extending from a root to a wingtip and having at least one interiorvolume, the method comprising: associating a pressure sensor for sensinga level of interior fluid pressure within the at least one interiorvolume with an alert system; and sealing the elongate body toencapsulate the at least one interior volume containing an interiorfluid; configuring the alert system to cease operation of a turbineassociated with the elongate body in response to the pressure sensordetecting the level of interior fluid pressure below, or above, athreshold level indicative of structural damage to the elongate body.10. The method of claim 9, further comprising: actuating at least onefluid pump in fluid communication with at least one valve connected tothe elongate body to pump additional fluid into the interior volumeincreasing a weight of the elongate body to an erratic wind resistanceweight while maintaining a desired interior fluid pressure.
 11. Themethod of claim 9, further comprising: actuating at least one fluid pumpin fluid communication with at least one valve connected to the elongatebody to remove interior fluid decreasing a weight of the elongate bodywhile maintaining a desired interior fluid pressure.
 12. The method ofclaim 9, wherein the alert system is associated with a hub or a nacelleconnected to the elongate body.
 13. The method of claim 9, wherein thesealing the elongate body comprises sealing the elongate body at theroot with a releasable and reusable seal.
 14. A turbine comprising: ahub; a plurality of structures extending from the hub and adapted totraverse a fluid environment exerting an ambient fluid pressure, each ofthe plurality of structures comprising: (i) an elongate body extendingfrom a root to a wingtip and encapsulating at least one interior volumecontaining an interior fluid exerting an interior fluid pressure that isdifferent from the ambient fluid pressure; and (ii) a pressure sensorassociated with the elongate body for sensing a level of interior fluidpressure; and an alert system in communication with the pressure sensorand configured to cease operation of the turbine in response to thepressure sensor detecting the level of interior fluid pressure below, orabove, a threshold level indicative of structural damage to the elongatebody.
 15. The turbine of claim 14, further comprising: at least onevalve, connected to each of the elongate bodies, configurable to enablefluid to be injected into or drawn from the at least one interiorvolume; and at least one fluid pump associated with the hub and in fluidcommunication with the at least one valve; wherein the alert system isfurther configured to, in response to the pressure sensor detecting thelevel of interior fluid pressure below, or above, a desired level,actuate the at least one fluid pump to increase, or decrease,respectively, the interior fluid pressure back to the desired pressure.16. The turbine of claim 14, wherein the interior volume is encapsulatedwithin the elongate body by a releasable seal.
 17. The turbine of claim16, wherein the releasable seal is located at the root.
 18. The turbineof claim 14, wherein the interior fluid is a gas with low chemicalreactivity.
 19. The turbine of claim 14, wherein the alert system isassociated with the hub or a nacelle.
 20. The turbine of claim 14,wherein the alert system wirelessly communicates with the pressuresensor.